#include<stdio.h>
#include<unistd.h>
int global_val=100;
int main()
{
  pid_t id=fork();
  if(id<0)
  {
    printf("fork fail!\n");
    return 1;
  }
  else if(id==0)
  {
    int cnt=0;
    while(1)
    {
     printf("我是子进程，pid:%d,ppid:%d | global_val:%d,&global_val:%d\n",getpid(),getppid(),global_val,&global_val);
     sleep(1);
     cnt++;
     if(cnt==10)
     {
       global_val=300;
       printf("子进程已经更改了全局变量。。。。。。\n");  
     }
     }
  }
  else
  {
    while(1)
    {
     printf("我是父进程，pid:%d,ppid:%d | global_val:%d,&global_val:%d\n",getpid(),getppid(),global_val,&global_val);
     sleep(2);
 
    }
  }
  return 0;
}
